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AMAZON multi-meters discounts AMAZON oscilloscope discounts Controllers are designed to allow the operator to switch the loop between open-loop control and closed-loop control. When the controller is set in manual mode, it's operating as an open-loop control system and the operator changes the output percentage to any value between 0% to 100% that's desired by pressing the up or down arrow keys on the face of the controller. The controller does not make any adjustments to the output on its own when it's in manual mode, even though the sensor continues to send a process variable (PV) signal, and the controller continues to display the PV. The operator may use the value displayed in the PV window to determine what the level is when adjusting the output percentage between 0-100%. When the controller is set in auto mode, it becomes a closed-loop controller and the PV signal is compared to the setpoint (SP) to determine the error. The controller uses the error in closed-loop mode to continually adjust the output. In this manner, the controller will automatically change the output to satisfy the SP. PREV: Single-Point (Single-Loop) Process Controller |